Dog owners are often confronted with the odour of their dogs’ faeces. Not only unpleasant, a strong smell is a marker for the release of harmful gases, e.g. ammonia. The excretion of such compounds by animals is common. Concerning husbandry animals, poultry trials have accumulated evidence for Calsporin® to drastically reduce the excretion of both, ammonia (Jeong & Kim 2014, Blair 2004, field trials) and the poisonous hydrogen sulphide (Jeong & Kim 2014). Supplementing Calsporin® significantly lowered ammonia emission of dogs (Felix et al 2010). Moreover, observations show significant effects on volatile fatty acids (Table 1). Beneficial bacteria are known to produce short chain fatty acids (SCFA), while pathogens typically produce branched chain fatty acids (BCFA). BCFA are the fermentation products of protein degradation, SCFA relate to carbohydrate metabolism. Calsporin® induces the combined effects of decreased ammonia and BCFA and increased SCFA, indicating the shift towards a healthier status of dogs’ microflora. Not surprisingly, the odour of dogs’ faeces therefore improves significantly by supplementing Calsporin® (Paap et al 2016).